﻿using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Web;

namespace ValidateCode.Service
{
    public class ValidateCodes
    {
        ///<summary>
        ///生成验证码
        ///</summary>
        ///<param name="length">指定验证码长度</param>
        ///<returns></returns>
        
        public string CreateValidateCode(int length)
        {
            const string validateTemplate = "0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
            string validateStr = "";
            int n = validateTemplate.Length - 1;

            //设置随机值生成器
            int seekSeek = unchecked((int)DateTime.Now.Ticks);
            Random seekRand = new Random(seekSeek);
            int beginSeek = 0;

            //生成随机验证码
            for(int i = 0; i < length; i++)
            {
                beginSeek = seekRand.Next(0, n);
                validateStr += validateTemplate.Substring(beginSeek, 1);
            }

            return validateStr;
        }

        ///<summary>
        ///创建验证码的图片
        ///</summary>
        ///<param name="containsPage">要输出到的page对象</param
        ///<param name="validateNum">验证码</param>
        ///<returns></returns>
        public byte[] CreateValidateGraphic(string validateCode)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 13.0), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random = new Random();
                //清空图片背景色
                g.Clear(Color.White);

                //画图片的干扰线
                for(int i = 0; i < 25; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);

                    g.DrawLine(new Pen(Color.Silver), x1, y1,x2 , y2);
                }
                Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));

                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

                g.DrawString(validateCode, font, brush, 3, 2);

                //画图片的前景干扰点
                for(int i=0; i < 100; i++)
                {
                    int x = random.Next(image.Width);

                    int y = random.Next(image.Height);

                    image.SetPixel(x,y,Color.FromArgb(random.Next()));
                }

                //画图片的边框线
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);

                //输出图片流
                return stream.ToArray();
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
    }
}